Liquid and energy are precious resources. In many geographical areas, the most accessible source of liquid is in the form of liquid. A ground water table, defined as a level at which the groundwater pressure is equal to atmospheric pressure, may be found within depths of a few tens of meters in many areas, including in locations that are otherwise far remote from any lake or river. Ground water is generally extracted using electric pumps that are located at the bottom of wells dug into the ground.
Energy, including electrical energy, is costly and may be of limited availability in areas where groundwater needs to be extracted. In some areas, groundwater availability may actually be high while electrical resources are limited and costly. Pumping liquid from other sources, such as a river or a lake also requires energy, which can sometimes be scarce.
Therefore, there is a need for economical techniques for pumping liquid and for generating energy.